We already know of various locking systems, commonly based on the principle of the engagement of a lock attached to the mobile part of the slide. This mobile part is attached to the seat, and notches are made in the fixed part that is attached to the floor of the vehicle. The lock is conventionally held in locked position, engaged with the said notches, by spring return means, unlocking being controlled by a lever which when operated disengages the lock from the notches and thus allows the slide to move and its position adjusted.
We also know, especially by document EP-A-117131, of slides made of a male section and a female section sliding one inside the other. The male section, which is generally U-shaped, includes on one side, forming an arm of the U, a set of notches in which, in locked position, the teeth or crenelations of a lock, attached to the female section, engage. This lock is installed so as to pivot around its center section on a shaft whose axis is parallel to sliding direction and held onto the bottom of the female section by a support. One side of the lock penetrates into the slide through an opening made in the bottom of the U forming the female section and houses at its end the said teeth, oriented in a direction perpendicular to the side of the male section including the locking notches, the teeth moving therefore substantially in this direction when the lock is rotated. A first return spring holds the lock in locked position. Unlocking is ensured by a lever hinged on a trunnion attached to the side of the female section. This lever includes a lug acting on the other end of the lock, located outside the slide, to pivot the lock in opposition to the return spring and disengage its teeth from the notches in the male section. This lever is returned to position by a second return spring.
The disadvantage of this system lies in the presence of many parts (support, hinge pin, springs), which complicates the installation and increases the costs.